'My dream': Federer explains amazing longevity

Andy Murray won't be one of them, but Roger Federer believes improved diet, greater professionalism and a shrinking world will lead to more tennis stars playing deep into their thirties.

Federer will match Lleyton Hewitt's record of 20-consecutive Australian Open appearances when he bids for an unprecedented seventh men's singles crown in Melbourne.

The great Swiss is promising to return again next year, at age 38-and-and-a-half, if he mounts yet another successful title defence over the coming fortnight.

"It's been a very emotional place for me to play here and I can't believe it's been 20 years plus juniors plus qualifying so it's been more than that actually," he said ahead of his first-round clash on Monday with Denis Istomin.

"To win another five-set thriller in the finals last year (against Marin Cillic) was epic. It was unbelievable."

Federer could have retired years ago, his legacy as arguably the greatest - and most certainly the most successful - player to grace a court.

Federer has tipped many of his peers to also play deep into their late thirties. Pic: Getty

But already with 17 grand slam trophies stashed away, Federer refused to pack it in even after breaking down during his 2016 Wimbledon semi-final loss to Milos Raonic.

At 35, he had unfinished business to tend to but insisted playing on had nothing to do with keeping clear of great rivals Rafael Nadal and Novak Djokovic on the grand slam titles leaderboard.

"I don't think I needed them to push me, to be quite honest," he said.

"It's more: 'How is my wife? How are my kids? How is my body? How are my results?

"And my goal was always to play for as long as possible because I have a lot of passion for this sport. I love playing tennis - always have.

"I've always tried to remind myself that this was my dream to become a tennis player, not that it became a job as such and that's why I think I'm able to show so much enthusiasm for tennis.

"So when I saw like Andre Agassi, or others, Ken Rosewall, Jimmy Connors play for a long time, I thought that was pretty cool, that they played through so many generations.

"So if I had a chance to do it as well, I'd be happy to try to go there as well."

Federer can barely believe he's still top 10, let alone world No.3.

"But that I'm still playing tennis as such, I feel with flying being more easy today than it was 20, 30, 40 years ago and that we're doing more rehab, more stretching, more massages, we eat probably better and we have a bigger entourage (it's not so surprising)," he said.

"I think all of that stuff is going to help a lot of the players play for longer, which I think is a good thing, that players aren't retiring at the age of 30."